Field Emission Cathode Using Microchannel Plate
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Solution Overview
Problem
Carbon nanotube-based field emission cathodes have a short lifespan due to carbon nanotubes being pulled out from the cathode electrode by strong electric field forces, leading to instability and reduced performance.
Innovation Solution
A field emission cathode design utilizing a microchannel plate with carbon nanotubes fixed inside the holes of the plate, where the nanotubes are connected by van der Waals forces and coated with conductive or secondary electron layers to enhance emission efficiency, and the microchannel plate acts as both the substrate and cathode electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If carbon nanotubes are printed on the cathode electrode, then the field emission cathode can be fabricated, but the carbon nanotubes are not secured and tend to be pulled out by strong electric field forces
Solution Approach 1:
The invention introduces a microchannel plate structure that segments the cathode electrode into multiple hollow channels. Carbon nanotubes are placed inside these confined channels rather than being printed on a flat surface. The channel walls physically constrain the nanotubes, preventing them from being pulled out by electric field forces while maintaining their field emission functionality.
Solution Approach 2:
The invention nests carbon nanotubes inside the hollow channels of the microchannel plate. The nanotubes are positioned within the confined space of each channel, creating a nested structure where the nanotubes are protected by the surrounding channel walls. This nesting approach secures the nanotubes in place while allowing them to function as field emission sources.
2Duration of action of stationary object
If carbon nanotubes are secured firmly on the cathode electrode, then the lifespan is extended, but the fabrication process becomes more complex
Solution Approach 1:
The microchannel plate serves multiple functions simultaneously: it acts as the cathode electrode structure, provides physical confinement for carbon nanotubes, enables field emission functionality, and offers a fabrication pathway through conventional ceramic or glass manufacturing techniques. This multi-functionality reduces the need for additional securing mechanisms that would increase complexity.
Solution Approach 2:
The microchannel plate utilizes a porous or channelled structure that is conventional in ceramic and glass manufacturing. These pre-existing hollow channels provide ready-made compartments for housing carbon nanotubes, eliminating the need for complex securing structures while extending cathode lifespan through physical confinement.
3Productivity
If carbon nanotubes are used for field emission, then electron emission efficiency is improved, but the cathode has short life due to nanotube pull-out
Solution Approach 1:
By segmenting the cathode into microchannel structures, the invention maintains the high electron emission efficiency of carbon nanotubes while preventing their displacement. Each channel houses nanotubes that remain in optimal positions for field emission, ensuring continuous high-performance operation over extended periods.
Solution Approach 2:
The nested configuration of carbon nanotubes within microchannel plate cavities preserves the nanotubes' field emission properties while providing mechanical stability. The nanotubes maintain their emission-oriented positioning while being protected from electric field-induced pull-out, thereby extending operational lifespan without sacrificing emission efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design improves electron emission efficiency and stability by securing carbon nanotubes within the microchannel plate, preventing them from being dislodged by electric fields, thus extending the cathode's lifespan and maintaining consistent field emission properties.
Implementation Method 1
the nanotubes are connected by van der Waals forces
Data Source
AI summary
The disclosure relates to a field emission cathode. The field emission cathode includes a microchannel plate, a cathode electrode and a number of cathode emitters. The microchannel plate is an insulative plate and includes a first surface and a second surface opposite to the first surface. The microchannel plate defines a number of holes extending through the microchannel plate from the first surface to the second surface. The cathode electrode is located on the first surface. The number of cathode emitters are filled in the number of holes and electrically connected with the cathode electrode.